ekos DSLR canon 5d MK3 only black frame - by: astropaul

Hi all,
I'm trying to take some photo of M42 with my canon 5D mk3 using ekos.
If I click on preview after to have set all parameter correctly (exposure, iso and so on) some times I'm able to see correctly the photo and some times I see only a black frame...
While starting the sequence... all photos are a black frame....

For example I stared the following sequence all at 800 ISO:
2017-03-28T20:13:41: Starting 120 sec exposure
2017-03-28T20:11:30: Starting 120 sec exposure
2017-03-28T20:09:20: Starting 120 sec exposure
2017-03-28T20:08:09: Starting 60 sec exposure
2017-03-28T20:07:29: Starting 30 sec exposure
2017-03-28T20:06:03: Starting 30 sec exposure
But all raw files are black...

The strange is that opening, for example with gwenview, the cr2 raw files, I see that for all this images the exposure time is 1/10....

Where I'm wrong???
Please let me know
Paolo